Memofest 2023, Where and When?

[stephen_usher]

The enhanced VDP stuff and 80 column card look interesting. Are you looking to upgrade it to be compatible with the VDP in the MSX-2 specification maybe allowing MSX-2 game ports?

[Bill B]

I hadn't thought about that. My initial interest was adding back some of the capabilities that the CFX-II has (using a Propeller chip).

It may depend on how much memory is required. The MFX has 32KB of video ram.

Do you have a reference for the MSX-2 specification?

[stephen_usher]

Hmm... Needs more RAM... https://www.msx.org/wiki/Yamaha_V9938

[Martin A]

Technically there's enough memory though for text 2 and graphic modes 3, 4 and 5.

MFX already has 80 column text support in basic using the VGA display, so there's not a great deal to be gained by adding text 2.

Mode 3 is currently half implemented, because of the expanded sprites. It's a question though of whether there is sufficient access slots to the SRAM chip to do them.

[davesnowdon]

Dave bought along his MTX512. It was the first one I have noticed as having the RS232 ports fitted. (Sorry no photo ).

Opening the case revealed an FDX interface board fitted, although Dave has never had an FDX.

I took a photo:

IMG_9796.jpeg (1.18 MiB) Viewed 746232 times

[gunrock]

Other topics that were covered during the day include:

• EPROM & PIC programmers using printer port.
• History of CFX, Propeller video & CFX-II leading to MFX.
• Andy's read-only PROM disk emulator.
• MTX_Lib and the Code::Blocks GUI for developing Memotech programs in C.[/strike]
• My implementation of a ZMachine interpreter for playing text adventure games.
• Martin showed his 3D printed, miniaturised FDX case for holding his REMemotech.
• Any use of PIO socket?
• CTC an asset for MTX.
• Jim gave a review of his porting of original MTX games to modern hardware (PCs and Phones).

Probably other things that I forget at the moment.

Wow! What a lot of great subjects that were covered. The ones that particularly appeal are the ones I have highlighted in blue. Any details on them?

BTW, the work on the MFX fpga code looks impressive, Bill. Particularly interested in the multi-colour 40 column text mode, the 12-bit colour support and the improved fonts with international keyboard support. Wonder if the Tektite font here might help: https://juanitogan.itch.io/p8-programming-fonts, has a cp1252 and a cp437 version, not sure what would be better?

Also honourable mentions go to Martin's FDX-midi case, MTXLib and the Z-Machine subjects (I love the Infocom games).

[Dave]

on the uses for the PIO, I mentioned the PAL reader that Tony Brewer designed for me
http://primrosebank.net/computers/mtx/p ... reader.htm

There are also quite a few legacy electronics projects listed here, such as a RTC for the MTX
http://primrosebank.net/computers/mtx/p ... legacy.htm

[gunrock]

Thanks Dave, I'd seen your PAL reader project before but missed the other projects.

It's a strange little expansion port, TBH, lower power draw only and it's inside the machine - which you have noted from selling various iterations of the CFX, a lot of folks have reservations on opening the case.

[Dave]

Yes, the port is only rated to supply 20mA, which isn't really enough (it initially caught us out on the MTX PS/2 keyboard project).
http://primrosebank.net/computers/mtx/p ... ps2kbd.htm

As you say, its location isn't really user friendly either

regards
Dave

[Bill B]

The CTC and the PIO port were both passing mentions towards the end of the day. Perhaps why I remember them.

I have made a lot of use of the CTC over the years:

• Both of my device programmers make use of the CTC to time the programming pulses.
• When I was developing my DIY Navtex receiver, the decoding software was developed on my MTX, using the CTC for timing. (I thought that at one time Dave had a page for this as it is Z80 based, but if so I can no longer find it).
• I have developed code to read and decode tapes saved from a BBC micro, again using the CTC for timing.

The CTC provides timing resolution of 4us, which is useful for many purposes.

Although not discussed at Memofest, I did at one time contemplate cabling from the PIO socket, to a 25-pin D socket in one of the spaces intended for the serial ports. Maplin used to sell insulation displacement connectors to go from ribbon cable to plugs for IC sockets. But they only ever had 16-pin versions, not 20-pin.

In the end, anything I might have used the PIO port for, I used the printer port instead. That provides 9-bits of output and 4-bits of input, and it is more conveniently located.