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@retrochallenge 2012 – Acoustic Coupling
Since contracting this retro computing bug, after prolonged exposure to Urbancamo, I’ve had a yearning to try to recreate one of my earliest and fondest computing memories. That memory, when recalled, still has the ability to send a little shiver of excitement down my spine. Picture the scene if you will, a musty old office in the maths block of my local upper school. Two spotty teenage boys, myself and the aforementioned Urbancamo. In one dingy corner of the room an ASR 33 Teletype, on the window sill an acoustic coupler and telephone and on a piece of paper, a phone number.
ADC 212 Internals
Thinking we were Matthew Broderick from WarGames we eagerly dialled the number inserted the handset into the coupler and waited excitedly for the Teletype to burst into life. Sure enough the ASR 33 started clanking away and we were in! Not NASA or anything like that you understand, but a nearby college upon which we were able to play a game called Shark Attack! A momentous moment in my computing history and the first and last time that I ever used an acoustic coupler.
Epson CX-21
I have for some time therefore been on the lookout for a working acoustic coupler that I could use to try to recreate some of that experience. After failing to bring back to life a very old Anderson Jacobson ADC 212 model, I was recently lucky enough to sport an Epson CX-21 on Ebay.
It’s in lovely condition, and the original NiCad battery even appears to hold a reasonable charge. It came with an Epson HX-20 in a custom-made case which no doubt accounts for its excellent condition. There was a little blooming on the rubber cups but I cleaned this off with a mild detergent solution and the whole unit looks almost new.
I will of course also need an old telephone with suitable handset and fortunately we still have a couple of 1970′s models at work that thankfully were never thrown out. These old BT models were built to last and the one I chose cleaned up really nicely, in fact it looks so cool I may use it in place of our current home set.
CX-21 Battery
The CX-21 only has two options to select, half or full-duplex and answer or originate mode. It has a standard DB25 port and I have the appropriate cable to hook it up to my PX-8, an Epson 724 cable. This is a modem cable with DB25 at one end and an 8 pin Mini DIN connector at the other. I have two options for terminal software on the PX-8, both previously downloaded, Kermit and Mex. The PX-8 does have a rudimentary terminal application on the built-in ROM but I’ve never had much success with it.
After charging the CX-21 and PX-8 I hooked up the TF-20 FDD and copied over all the software I’d need to the PX-8′s RAM disk so I had the minimal amount of stuff to take home from where I would be calling back to the box running my BBS.
Epson PX-8 With The CX-21
I then spent rather too long trying to get my head around whether I was originating or answering the call, clearly I was originating it and the BBS box was answering but for some unknown reason I’d convinced myself that the coupler would have to ‘answer’ the handshaking attempts of the remote modem.
Nevertheless once sanity had been restored I set the coupler to ‘originate’ mode at full-duplex and dialled the BBS with the telephone. After several attempts the ready light finally illuminated on the coupler and it seemed a connection had been established. However once I’d connected via the terminal software all I received was a screen full of garbage.
I checked all my settings, made sure background noise was minimal and continued to make many more attempts to create a good connection. Eventually I discovered that contrary to my instinct to push the handset more deeply and securely into the coupler, lifting the mouthpiece end slightly out of the cup resulted in a much better connection! Whether the proximity of the transducers was causing some sort of distortion I don’t know but whatever the reason I now had a working connection and was reliably able to re-create it. There are still a few erroneous characters coming through but I can live with that.
I shot a quick video showing the process below, all I need now are a couple of ASR 33′s.
BBS’ing With The Epson PX-8 Geneva
I’d hoped to acquire an acoustic coupler to use with the Epson PX-8 however it wasn’t to be. Plan B involved connecting up an external modem and I therefore needed some software that would allow me to communicate with the US Robotics unit that I have, Mex from NightOwl Software was the obvious choice.
Using this guide I was able to determine which files I needed specifically for the PX-8 which were as follows:-
- MEX114.COM
Assembling MEX PX8 Overlay
- MLOAD25.COM
- MXO-PX8.ASM
- MXO-SM14.ASM
- ASM.COM
- MEX.HLP
The MXO-PX8 overlay is I believe written specifically for the Epson Multi Function Unit which has a built in modem and sits below the PX-8 connecting via the system bus. It is therefore also necessary to include a generic Hayes compatible overlay if you need to communicate via RS232 with an external modem.
Generating MEX For The PX-8
I used Filink to move all the files that I needed across to the PX-8 and saved them on disk with the TF-20 and used ASM.COM to assemble the overlays. Using MLOAD you can then generate a MEX executable tailored specifically to your PX-8/Modem set up.
Epson Cable 724
In order to connect a modem to the RS232 interface on the PX-8 you need the Epson 724 cable, which is mini din to DB25. Fortunately one of my PX-8′s came with this cable and it’s not to be confused with the similar looking 725 cable which is a null modem version.
Px-8 & U.S.R. Modem
So then the moment of truth, what chance this would all work? I decided I should try and find a dial up BBS other than mine own to try. Wgoodf’s recent blog entry pointed me in the direction of the Plasma Sphere BBS which I didn’t have any luck with but this did lead me to the Arcade BBS.
A nice feature of MEX is you can use either ‘Call’ or ‘Dial’ to initiate the call, the latter will allow you to drop back into the command line and fire up other software if necessary, Kermit for instance. I stuck with ‘Call’ initially and it worked! Sort Of. Clearly there are some issues, I’m guessing buffer overruns but I’m sure these can be ironed out.
So here’s a video of me connecting to the Arcade BBS with my Epson PX-8 using Mex:-
(Update, I restricted the RS-232 port to 300 Baud and tried again with better results and have therefore updated the video, ahhh 300 baud, those were the days.)
Epson PX-8 PF-10 & TF-20
Having declared in an earlier post that I’d managed to get the PF-10 working again I thought I should really post some proof.
I apologise for the shaky, and frankly poor quality of this video, I forgot my tripod and camera and had to fall back on the iPhone.
I just show the PX-8 going through the available drives:-
A: Ram Disk
B: Basic ROM
C: System ROM
D: TF-20 5.25″ FDD 1
E: TF-20 5.25″ FDD 2
F: PF-10 3.5″ FDD
H: Mini Cassette (Realised I forgot this, bless it)
Commodore 128D and CP/M
I shall be away for the beginning of this year’s Retrochallenge, so in order to hit the ground running when I get back I thought I’d make sure all my machines were primed and ready for action. To that end I’ve recently sorted out the batteries in my PX-8′s and today my attention turned to my Commodore 128D.
The machine is in pretty good condition, the cassette port is a bit flaky and the built in 1571 drive seems to read and write to disks reasonably successfully. My interest lies in using CP/M on the C128 and I really needed to secure a way of getting data into the machine in this mode.
This has caused me some considerable headaches, in its native or C64 mode the machine uses Group Character Recognition (GCR) to write data to the disks in the 1571. The 1571 is also capable of writing Modified Frequency Modulation (MFM) disks as used by CP/M and under CP/M disks using the following formats can be read:-
- IBM PC CP/M-86
- Osborne 1
- Epson QX10
- Kaypro II, IV
- CBM CP/M FORMAT SS
- CBM CP/M FORMAT DS
With third party software such as Juggler even more formats are supported.
Armed with Big Blue Reader, the original CP/M system disk, a clutch of DSDD disks and my bridge machine running DOS and 22Disk I thought I was well prepared. However no matter which combination of disks and formats I use I cannot successfully format a disk with the 1571 nor the 1581. I’m pretty sure the disks are OK, they seem to work without problems with the Epson TF-20 and PX-8 and the 1581 and 1571 drives appear happy to do everything except format.
More in desperation than hope of success I put one of the disks that I’d formatted with the TF-20 and PX-8 in the C128, typed DIR. To my surprise and excitement the C128 came up with some text at the bottom of the screen reading Epson QX-10. I pressed return and the drive chugged away, thought about it for a while and came back with ‘No file.’ uh, there were definitely files on the disk.
I had a search around and discovered that when the format description comes up at the bottom of the screen you can cycle through different options. So I tried again and using the right arrow key found the next selection was ‘Epson Euro’ I pressed return, the drive chugged away and up popped the disk contents, yipeee!
I loaded PIP quickly just to check it worked, which it did and I then formatted a fresh disk in the TF-20, copied the text adventure Snowball onto it and put it into the C128. On the first attempt I got a BDOS error but on the second attempt it loaded.
So I now have a way of getting software downloaded from the Internet into the C128 in CP/M mode, albeit a somewhat circuitous route via the PX-8 but a way nonetheless.
I currently have the C128 hooked up to an IIyama LCD panel via the s-video port which means I can only run in 40 column mode however I do have a cable that will allow me to connect via Scart and run in 80 column mode which I shall try next as much of the software I’ve tried assumes this mode.
So now hopefully I’ll be able to get on with things as soon as I return, try some CP/M software on the C128, hopefully get it talking to the Epson PX-8 via RS232 and I have some unused 3.5″ DSDD disks on the way which I’m hoping I’ll be able to format successfully with the 1581.
Kim Kimberley, Zork & CP/M
I had a spare hour or so today and decided to hunt around for some games for my PX-8. Given the limitations of the display and my own fondness for interactive fiction I decided to see what text adventure games I could find for CP/M.
A quick search for CP/M games took me immediately to the Retroarchive where I’m pleased to say the first three games of Infocom’s excellent Zork series were to be found along with a number of other games.
Pleased with this result I wondered if there were any CP/M versions of Level 9′s adventure games out there and I quickly found Snowball and Lords Of Time here.
Annoyingly my plans for a bridge machine with both USB and network support remain exactly that, plans, for some reason Filink will not run on the Pentium III under DOS and I have therefore been forced to resort to my Fujitsu in order to transfer files to the PX-8. The downside of this is I have to burn a CD every time that I want to transfer files downloaded with my Mac on the Fujitsu for transfer to the Epson.
Nevertheless I was soon transferring the games I had downloaded with Filink from the Fujitsu directly on 5.25 floppies via the PX-8 (picture below.)
All of the Infocom and Level 9 games appear to be working fine. Some of the location descriptions are too long for the PX-8 to display without some of the text scrolling out of view and if I’m honest the LCD on the Epson is not one of the best I’ve seen, in fact the PX-4 has a much better screen with clearer better contrast.
However the keyboard is a joy to use, it has that lovely clackety clack that you don’t seem to get with modern day equivalents so I shall get stuck in again to the world of Zork and see what I can remember.
I’ve copied Zork 1 to the ram disk and will store my save games on cassette for the shear hell of it.
I am indeed standing in an open field west of a white house, with a boarded front door. Maximum verbosity.
That reminds me, I’m sure there was a another version on the Vic 20 called The Colonel’s House? Oh, and I’ve also discovered that you can play Zork in your browser at ifiction.org.
Epson PF-10 Disk Drive Working Again
I recently stripped down my two PF-10′s and managed to reassemble one working drive from the components. The drive is working quite well, the only real problem is the battery is only lasting about 30-40 minutes before needing a lengthy recharge. However this at least gives me enough time to perform a few tasks.
Today I formatted some disks using Copydisk, I found some old 1.0 MB double sided double density disks which seem to work well, the high density ones that I tried did not work. I then daisy chained the TF-20 and the PF-10 to the PX-8 by running the cable from the TF-20 into the back of the PF-10. This required opening up the PF-10 battery compartment in order to flick a dip switch to ensure there were no drive letter conflicts.
This set up gives you the PF-10 as drive F and the TF-20 dual drives as D and E. The PF-10 came with some old disks and I took the opportunity to copy their contents using PIP onto some 5.25″ disks just in case the PF-10 dies again. This included some original copies of Microsoft Basic and Compiler. That proved to be enough work for the main battery and the back-up battery light began to flash. It’s a shame the unit won’t run off of the AC adapter however I’m just thrilled it’s now working at all.
I shall use Filink to further back up the files I transferred today onto my bridge machine and I shall see if there’s any chance of building another working PF-10 from the left over components.
Epson TF-20 Boot Disk Creation
As I mentioned in an earlier entry, the Epson TF-20 5.25 inch floppy drive requires its OS to be loaded from disk before the unit will communicate and work with the PX-8.
My over riding intention since acquiring the TF-20 has been to back up the single boot disk that came with the system given that it’s over 20 years old and should the disk have failed the drive would have been rendered useless.
My initial attempts failed, although I have a copy of Copydisk and it was apparently successfully formatting and creating disks with the system tracks, when I tried to boot the drive with those disks, no luck.
I spoke to F J Kraan who advised that the proper disk type was Double Density (DD) as opposed to the High Density (HD) that I was using. I tracked down some DD disks and repeated the process and it works. I have of course therefore made several back up boot disks and feel somewhat relieved.
Incidentally the HD disks give the impression of working for general file usage, but success is intermittent, with occasional bad sector errors. Meanwhile the working PF-10 has decided to well, stop working, hopefully this last burst of activity wasn’t its last hurrah.
I’m waiting on some C size batteries to try in the drive to see if it’s a battery issue or not. Meanwhile I took one of the PF-10′s apart and took some crumb trail pictures with my phone.
(Update:- I’ve installed the four new C size batteries in the PF-10, but still no joy, harumph!)
Epson PF-10 Success & Ram Disk Failure
Well it seems Epson PF-10 floppy disk drives are somewhat like buses, you don’t see any for ages and then two come along at once. Much to my surprise given what I’d read and been told about the rarity of the PF-10, another one appeared on Ebay.
This one was listed along with a PX-8 which I didn’t really need however I decided it was worth bidding just to acquire the drive. I duly won the auction, the PF-10 arrived and… it works!
It’s a bit temperamental but I like a challenge. It’s in very good condition, especially compared to the rather beaten up drive I previously bought and it is sitting right next to me now, looking all Silent Running like, and somewhat dwarfed by the TF-20.
Thus far I’ve managed to read, write and format some disks with it, the battery is a bit flaky and the drive unfortunately won’t run of off the power adapter, although it will take 4 C type standard batteries if required. I’m going to swap out the battery for the one in my other drive which seems more successful at holding a charge. I’m also going to set the required dip switch so I can daisy chain it with the TF-20.
As a bonus (I hadn’t noticed it in the picture) the accompanying PX-8 was fitted with an external RAM disk which I had been on the look out for anyway. Unfortunately it’s currently giving me BDOS errors whenever I try to access it. I’m hopeful however that this is an issue with its batteries as opposed to any other damage. I took it apart to confirm that battery type which turned out to be an Epson RB 101, 4.8V 500 mAh.
I’ve taken some pictures, unfortunately they are with my phone so I apologise for the quality, I’ll hopefully be able to take some proper photos soon, note the cheesy 70′s wood panelling, very apt.
Madame Fifi’s Whorehouse And Other Tales
I continue to tinker with my growing collection of old Epson computer equipment. The TF-20 is a strange hulk of a drive. Rather like the old Commodore 1541 the drive has a processor of its own comparable to the computer it serves.
In the case of the TF-20, a Z80 supported by 64 kByte of RAM (presumably these things cost serious money back in the day.) In order for the drive to work with systems such as the PX-8 you must first load the drive’s OS from a system disk. This is causing me some concern as I only have one disk that will boot the system and if that fails the drive will be essentially useless to me.
Along with the drive came a few 5.25 inch floppies with an eclectic mix of files on them. Two that caught my eye were Diskcopy and Copydisk. My first inclination was to try and make a couple of backups of the boot disk.
I thought I’d found what I needed with Copydisk which gave the following options:-
- Format
- Copy System Tracks
- Copy Complete Diskette
- Format and Copy System Tracks
- Format and Copy Complete Diskette
- Initialize Directory Tracks
After placing a write protect sticker over the notch of the boot disk (this reminded me of using scissors to cut out notches on the opposite side of disks so you could use both sides) I pretty much tried every combination of these options with some new blank disks I’d managed to find on ebay.
Whilst the formatting and copying all worked well, none of the newly created disks would boot the system so for now I’m relying on the squeeky old boot disk. The OS will remain in memory as long as you don’t disconnect the power cord from the TF-20 however the onboard power adapter gives off the sort of aroma that makes you want to stick a smoke detector directly over it so I’m not relaxed about leaving the power connected.
I’ve also been sorting through the fairly large collection of PX-8 related files I’ve downloaded and have transferred a few basic games via Filink directly onto floppy. There’s a certain buzz from loading these files with no real idea what you’re going to be presented with. I think the most surprising so far was FIF which turned out to be Madame Fifi’s Whorehouse, a somewhat lewd text adventure game.
A lot of the files have extensions such as CQM, DQC, BQS which I initially thought had perhaps become corrupted given their similarity to COM, DOC, BAS however on investigation it transpires these are files compressed with a program called SQ which replaces the middle character of all the files it archives with a Q. So far I’ve been unable to find a way of opening these archives.
(Update)
Thanks to Chuck over at the Vintage Computer Forum who pointed me in the direction of the source files and executable of Unsqueeze at the Retroarchive and to the DOS version
Epson TF-20 5.25 Inch Double Floppy Disk Drive Pictures
As yet no joy with the PF-10, the unit spins up but I’m getting bad sector errors on all the disks I try to access. I’m not particularly surprised, in fact I would have been more surprised if it had worked. However I shall try and clean the heads and have a poke around to make sure everything that should be moving freely is doing so.
More luck with the TF-20 which is in fine working order. Both bays are working well and I’ve managed some read and write operations on both. The unit itself in monstrously heavy, most of the weight is I assume coming from the built in transformer. So far I’ve tried the unit with a PX-8 and PX-4. Along with the PF-10 the TF-20 came with a huge bundle of PX-4 related items. The PX-4 itself, several spare keyboards, a couple of cassette units, a ram disk and a rom holder all of which are interchangeable on the PX-4 (also apparently known as the Epson Pine.)
I also have some promotional literature for the PX-4 and an original UK price list which I’ll scan in and post. For now some pictures of the TF-20.
