Retrochallenge In A Day, Sort Of

January 28, 2016January 28, 2016Retrocosm 5 Comments

I began this day intending to start and finish my Retrochallenge for Winter 2016. Of course given the on-going saga of my working and then not so much working Epson PF-10 portable floppy disk drive units, it would have fallen to virgin readers only to be amazed by my expeditious achievements.

Honesty however must prevail and this, my latest attempt to breathe reliable, long term life in to my PF-10 follows an infamous litany of countless failed attempts.

Each attempt has however brought me closer to this final crowning glory (spoiler alert.)

It’s the battery stupid. Yep, NiCd, 30 years plus old, kind of makes sense really, especially to those of you who have completely ruined Retrochallenge by actually knowing what you’re doing, you with your big brained entryism.

A brief re-cap, the PF-10 has two batteries, both NiCd. The main battery, removable, sits in a tray at the back. If necessary it can be substituted for four LR14 dry cells.

The second battery resides internally and is intended as a backup for when the main battery runs low. An LED on the front of the unit will light when the backup battery has been engaged and will flash when it starts to run low.

Initially, imagining that the main battery was probably an ex-battery (despite no leakage, none of my myriad of Epson NiCds have ever leaked) yet armed with the original power supply, duly plugged in, I naively imagined the unit would work, you know, power from the wall socket plugged in, power.

BDOS ERR ON D: BAD SECTOR

This I had concluded would be my epitaph, given the amount of times over the years I’ve sat staring at this message, often less than clearly displayed on the PX-8’s low contrast display.

To cut a tediously uninteresting story short, the on-board backup battery is required to hold a decent charge for the unit to work, regardless of how much power is being supplied from the main battery or power supply.

The hunt began to find a suitable replacement NiCd battery, no luck, I tried a NiMh, some luck but of course the on-board charging circuit is not suited.

Thus we find ourselves here today with the end looming of Retrochallenge 2016. I found a NiCd, it has arrived, I have charged and connected it and yes it works. Does it fit? No, certainly not in the space inhabited by the original cells. Not to worry however, surely it will fit the main battery compartment, no, you’d think it would but it’s off by about 4 mm.

So there you have it, I’m a ‘finding the right size battery’ away from success. But I’m calling it, and that’s all that matters.

Retrochallenge in a day (or plugging in a battery,) beat that you losers.

P.S. I even used old pictures so I shot some shoddy video to show it working:-

Televideo TS-802H

October 22, 2013October 24, 2013Retrocosm 3 Comments

Currently on the work bench and satisfying at last my search for a machine with a gorgeous, phosphorescent green screen is a Televideo TS-802H. This hybrid machine is similar in many respects to the DEC VT180, a terminal with the option of running as a stand alone CP/M based computer. The ‘H’ denotes that this model is configured with a Winchester HDD and a single 5.25″ FDD. As is typical of the era this was the more expensive option over the standard dual FDD configuration.

Specifications are as follows:-

CPU – Z80A @ 4 MHz
Memory – 64K RAM
Diskettes – 5.25 inch soft sectored, 256 bytes/sector, 18 sectors/track, 40 tracks/side, DDSD, 368K
Hard Disk – Single Winchester, 7.47 Mb formatted capacity (Rodime RO-200/2 10 Mb)
Transfer Rate Floppy – 250 kilobits/second
Transder Rate HDD – 5 megabits/second
IO Ports – 2 x RS232C ports, 150 baud – 19.2 kilobaud, 1 x RS422 port, 800 kilobits/second
Screen – 12 inch phosphor, 80 characters x 24 lines
Operating System – CP/M 2.2
Power Consumption – 0.65 amp max at 230 VAC

Disassembling the TS-802H

On arrival the machine was fully operational with the exception of the FDD which would not read any of the media that I tested.

The HDD had 3 partitions and along with the operating system there were mostly data files belonging to the company that had originally owned the Televideo.

There were also a few games, Polish Pong which was not something I’d seen before along with more familiar titles such as Star Trek.

The HDD Controller

Unfortunately the following day the HDD would no longer boot the system and with the FDD not working I was left with a nice looking, but rather bulky terminal.

With the DEC Legacy event imminent I decided to take the Televideo with me to both show off the machine and seek advice on the hardware failures.

Cleaning the FDD heads

Suggestions for addressing the HDD issues ranged from taking the unit out and hitting it on the table to lifting the top cover and checking for obvious jams, stuck heads and misalignment.

On return I disassembled the machine and removed the FDD and HDD. I cleaned the heads on the FDD, cleared various detritus from the mechanism and checked everything was moving freely.

Formatting floppy disks

Next I proceeded to remove the screws from the top cover of the Winchester with the intention of lifting it and having a peek inside. Then I bottled it, replaced the screws and gave the whole unit a couple of flat thwacks on the desk instead.

With the gubbins of the machine removed I took the opportunity to vacuum the case which was thick with dust.

On reassembly I was thrilled to find that the FDD would now boot from the original system floppy. On doing so the machine reported that the HDD was either uninitialised or faulty. I noticed however that the HDD was definitely spinning again, it was making the tell-tale squeaking noise which had been absent on the last few power ups.

Formatting the HDD

I loaded up HRFORMAT from the system floppy and reformatted the HDD. This process was apparently successful.

Using SYSGEN I was able to copy the CP/M system files to the HDD and create a bootable drive.

Setting the appropriate DIP switch on the rear of the unit I set the Televideo back to boot from hard drive, did so, and then formatted some fresh floppies and backed up all the files that I could.

Unfortunately some of the files that were originally on the system were lost in the process but I don’t think there was anything on there that isn’t freely available.

However I now need to think of a process for successfully transferring software onto the machine.

Vintage Computer Festival GB, Snibston July 2013

July 5, 2013July 15, 2013Retrocosm 1 Comment

I travelled up to the VCF-GB today at the Silicon Dreams event at Snibston Discovery Museum and took the opportunity to capture a few pictures. It was pretty quiet being a weekday but I suspect it will be somewhat busier over the weekend.

I arrived pretty early and a number of exhibitors were still setting up. AmigaKit, Amiga North Thames and A-EON were not present when I was there although I did get to see Morph OS running on a Mac Mini G4, demonstrated by a very helpful and enthusiastic Ravi Abbott. I happen to have a Mac Mini G4 and will have a play with Morph OS later.

The BBC classroom was all set up and running, a most peculiar experience to see such a set up again. Had my previous Retrochallenge not revolved around programming the BBC I probably would have taken the opportunity to have a play.

In various rooms around the museum there were rows and rows of computers and consoles set up ready to be played with and I took full advantage. I felt my age when I witnessed a young lad trying to insert a 3.5″ floppy disk the wrong way round, seemingly completely unfamiliar with the technology.

I spoke at length to Dylan Smith of Spectranet fame who has developed the ZX Spectrum ethernet adapter utilising the WIZnet 5100 chip. I not only admired the finished product but Dylan’s extraordinary soldering skills on the prototypes. I also saw a working Harlequin board which was very cool.

I missed the IBM SYSTEM/360 Recreation which was pretty disappointing, not sure if they simply hadn’t set it up but I was really looking forward to that. I would also liked to have seen more equipment from the 60’s and 70’s.

Here are some pictures and video, as you can see it was very quiet on Friday morning so little opportunity to capture visitors interacting with the exhibits. If possible I may travel back up on Sunday to see if some of the missing exhibits have appeared.