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A Chap on the Powertran Cortex Forum has made a Homebrew Mini-cortex micro complete with PCB. Specs are U1 TMS9995 U2 74LS612 U3 74LS14 U4 AT28C256 U5 628512-55 U6 74HCT688 U7 Sparkfun slim CF Card Board U8 TMS9902A U9 Elektor FT232R Board U10 74LS259 U11 GAL22V10D U12 74LS74 U13 74LS112 U14 74LS138...

An impressive port ... looks good ! But How many games are out there for the Sord M5 ? The Sord M5 was a rare beast ... must be hard getting games for it ?? And how many were any good ?? which ones are worth porting ??

I was reading on the 'Vintage Computer Forum' that a NEW TMS9900 Powertran Cortex is in the pipeline. http://www.vintage-computer.com/vcforum/showthread.php?15580-Powertran-Cortex/page79 It looks like it will be based on the TMS99105 CPU, and by what I can gather it looks like some of the original d...

Using Fast CPLDs instead of GALs..: One solution regarding speed is to possibly use fast CPLDs :EPM7064SLC44-7 (7.5ns 44 pin) rather than GALs , you can get some quite large GALs but anything bigger than a GAL22V10 will need an expensive programmer ? Though large CPLD are either in PLCC for surface ...

There's also the problem of I/O read / writing at high speeds. The need to insert WAIT states may counteract any further speed increases above 32MHz? As the I/O bus will be needed to be slowed down to 4MHz or so to communicate with peripheral chips?? It may prove 32MHz is the optimum speed ?? Also 3...

SRAM speed ratings What SPEED rating is needed when running at 32MHz and 40MHz , as legacy static ram (SRAM) are normally 55ns,70ns,85ns or 100ns. 32K SRAM or 128K SRAMs 70ns,85ns,100ns speed ratings 512K SRAMs 55ns or 70ns 32k or 64K fast SRAM 15ns (UM61256 , UM61512 type) So I'm assuming your usin...

Are there any heat or stability problems with over-clocking to 32MHZ ?? I'd assume that at 32MHZ a Z84C0010PEC will get warm especially if left on for several hours ?? I'd read that the PLCC versions have less capacitance between pins and thus more easily over-clocked .. but this may not be an issue ?

The only possible way to reduce board size without reducing chip count is possibly switching to using PLCC ICs where possible. PLCC ICs aren't much liked, as it's more difficult to BreadBoard your design with them, however once the design is complete then using PLCC ICs is an option. Also the PLCC I...

Also in RUSSIA I believe they use the SECAM TV standard, as does FRANCE.. so that's probably why the GR8BIT uses a TV to VGA adaptor ?

Spotted a Homebrew V9990 board on MSX.org Forum

http://www.msx.org/forum/msx-talk/gener ... ent-258676

not necessarily MTX related, and the V9990 IC I believe is not backwards compatible with the TMS9918/V9938/V9958 VDP but still quite interesting.