JFF - MSX 1 Compatible Computer

Supporter (11)

01-04-2023, 15:29

Hi
I want to show you a project. The goal was to build as simple as possible, but fully functional MSX 1 compatible computer. More details are available at the following links: JFF project on GitHub and JFF prototype on YouTube

Specification:

Processor: Z80 CPU
Memory: 64KB in SLOT3
Video: TMS9918A - NTSC 60Hz - Composite video output
Audio: AY-3-8910 or YM2149F
Two cartridge slots
Two joysticks ports
Casette port

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Por Danjovic

Champion (344)

01-04-2023, 16:36

Awesome!!!!
I have browsed the project on github. Nice work on the schematics, as they are very easy to follow, and I have enjoyed the LM311 used to enhance the cassette reading. One remark, though is that the PNP transistor Q2 that controls the cassette relay should have its load (the relay coil) on the collector instead of on the emitter.

Por skoti

Supporter (11)

01-04-2023, 18:18

Hi Danjovic
Thank you for your comments. I don't think there is a problem if the load is on the emitter side. But maybe i'm wrong. Switching the relay works correctly. Anyway, Philips VG8020 also has a relay on the emitter side in its schematic.

Por tulack

Resident (33)

13-05-2023, 10:05

congratulations on the project. You will tell us.

Por aoineko

Paragon (1138)

13-05-2023, 11:15

Nice project. It is like the Omega of the MSX1.

Out of curiosity, what BIOS are you using?

Por skoti

Supporter (11)

13-05-2023, 16:01

I'm using a custom built BIOS for JFF with an international keyboard layout and in a second ROM bank BIOS from Canon V-20 JP.

Por aoineko

Paragon (1138)

13-05-2023, 16:18

"Second ROM bank BIOS" is BASIC parser and functions?

Por skoti

Supporter (11)

13-05-2023, 17:22

I meant that in JFF you can install a W27C512 chip programmed with two different BIOS switched by jumper.

Por sdsnatcher73

Enlighted (4299)

13-05-2023, 17:40

Very cool. On the relay of the VG8020, not sure if this computer is the best to look at on this matter. I have seen and tested many MSX computers over the past 2 years and only in the VG8020 did I find the tape relay to be broken (several machines with this issue). No other (or very little, can’t be very certain) machines had issues with tape relay.

Por crisag

Expert (122)

14-05-2023, 20:32

This is cool. Will build one of those for fun! Congrats @skoti!

Por skoti

Supporter (11)

14-05-2023, 22:15

sdsnatcher73 - I will change it in the next revision.
crisag - Great. Let me know how it goes.