Memofest 2014

Memofest 2014 was held on 20th September, at my place.

Tony Butterfield, myself, Mark Kinsley, Jim Wills, Claus Bækkel, Simon Clewley, Mike Rudkin and Vince Sethi attended. Dave Stevenson attended virtually, via Skype.

Things that were there included :-

Clauses and Mikes REMEMOrizer were both upgraded to r3. I demonstrated REZSPEC and also the Mandlebrot generator running on a normal MTX (MEMU) verses REMEMOrizer.

Mikes FDX didn't boot properly, and this was traced down to a problem with D1 signal, somewhere on the FDX side. When the Z80 reads the CP/M boot ROM, D1 is always 0. We suspect this could be ribbon cable related, either external to the FDX case, or more likely within the case, probably where the ribbon cable meets the bus interface card.

The MTX that Mike uses with his REMEMOrizer didn't switch to MTX BASIC properly. In this system the OS+BASIC ROM should have been removed. It seems that the OS+BASIC ROM and the ASSEM ROM had been removed, and the OS+BASIC ROM plugged back into the ASSEM ROM socket. The problem was resolved by programming a new ASSEM ROM.

Another of Mikes MTXes was investigated and appears to either have bad VRAMs, or VRAM circuitry. The VDP itself was fine. Although I've successfully replaced VRAM in the past, this is not something I was prepared to take on during the day, and I didn't have any VRAMs in my box of electronic components anyway.

Another of Mikes MTXes produced the dreaded black screen with tone. Using the testcard ROM worked, pointing to dodgy DRAM. We then disabled the onboard DRAM (and ROM), and plugged in a REMEMOrizer to provide this instead, but the problem remains. So this points to something (DRAM?) pulling the data bus high or low, or shorting etc..

Mikes video wall kit included one of the MTXs, a video unit, and the main "black magic" box with 2 controllers and 9 framestore cards. I suspect that each of the 9 9-pin D framestore outputs has the same pin-out as the FDX or SDX 80 column RGB output, and would therefore drive the same kind of monitors. The MTX was an S2 with RS232 card and a ROM card. The ROM card had the RSCPM boot ROM and an initial RAM disk containing VW94.COM and supporting files. VW94.COM is for a 4x4 wall, and yet we only had 9 framestore cards - is Mike missing an extra black magic box? The "Videowall Controller" MTX was one of Mikes bad ones, but we were able to run this software by putting the ROM card in another known good MTX. We were also able to run the MSDOS VW.EXE version on an old laptop. The big stumbling block was getting these programs to talk to the controller cards over the centronics cable. It has to be said, the cable did look very tatty, and did have wires that weren't connected. The MTX software said "no sync", and the DOS software got stuck trying to send for a long time (although it didn't actually say "timeout").

Mike found a willing victim to take the video wall off his hands.

Martins MAGROM was demonstrated, and it was generally agreed this is the easiest way to load games on the MTX.

Martins Text Invaders was unveiled and we all tried it. It was rather good and has been added to MEMU and REMEMOrizer SD Card.

Claus unveiled his new port of SASA to the MTX. This game runs fine on MTX, but on a 3.57MHz Coleco with 60Hz screen refresh, it slows down. The slower clock speed, the fact that M1 cycles incur an extra wait state, and the 60Hz screen refresh all mean that the game has fewer cycles to do its thing each frame. A couple of opportunities for code optimisation were identified.

Dave Stevenson generously supplied a MAGROM as a prize for the best software submission, but as the only new submission was Text Invaders and this was not eligable, another criteria had to be devised. After some discussion, and considering who already had a MAGROM, and who might benefit most from one, Simon was deemed to be the most worthy recipient.

Tony brought some 5.25" floppies. I couldn't read them on my old style SDX, and in fact a quite nasty grating sound was heard, and we think a head clean is probably in order... Jim identified incorrect cable direction inside Mikes SDX drive which got it working, and using this drive, we identified 2 of Tonys floppies as having content worth recovering.

During the day we also tried using Marks new PSU to power the Videowall Controller MTX.

The DMX80 and Memopads went to Mark, most of the tapes went to Claus and a few bits-n-bobs from the electonics box such as the EPROM programmer found new homes too.

Breakfast was provided, including pancakes. A cold meat platter and cheeseboard was for lunch. The piece de la resistance was the Memotech themed cake. A large number of very bad computer related jokes were made about the cake. Finally at dinner time, a selection of pizzas were ordered.

The disappointments of the day were that we weren't able to pick a day that everyone could attend, that the Skype connection to Dave was so intermittent, that we didn't get further with the hardware diagnosis, and that we didn't get to construct a node ring.

Again, all in all, a very busy and great day.

This page maintained by Andy Key