Search found 60 matches

by monsonite
30 Apr 2019, 17:55
Forum: Hardware and software hacking
Topic: 10MHz, 12.5MHz and Beyond!
Replies: 24
Views: 2784

Re: 10MHz, 12.5MHz and Beyond!

Further progress this evening with the arrival of a 13MHz crystal. Tetris still runs perfectly, WozMon runs perfectly, TinyBASIC runs intermittently. Mandelbrot runs for several "loops" but crashes to black screen when trying to render the 24th scan line from the bottom of the screen. At 12MHz all i...
by monsonite
29 Apr 2019, 16:54
Forum: Hardware and software hacking
Topic: Indirect Addressing?
Replies: 8
Views: 648

Re: Indirect Addressing?

IMO we would be better off adding a parameter to ALLOC, LDLW, and STLW that refers to a 2-byte ZP location that is used as the base address for the stack. This would allow e.g. the C compiler to save some time and space when manipulating the stack by using these instructions rather than helper call...
by monsonite
29 Apr 2019, 12:33
Forum: Hardware and software hacking
Topic: Indirect Addressing?
Replies: 8
Views: 648

Re: Indirect Addressing?

Marcel, This sounds like an interesting alternative. I'll have to look more carefully at ALLOC, LDLW and STLW and get them coded into the simulator. BTW - I have ordered 13MHz crystal, 10nS 128Kx8 RAMS and SOP32 to DIP32 adaptor boards. I hope to get the expansion board built up and include a fast R...
by monsonite
28 Apr 2019, 19:45
Forum: Hardware and software hacking
Topic: Indirect Addressing?
Replies: 8
Views: 648

Re: Indirect Addressing?

Hi All, Now that we have a cpu capable of 12.5MHz (at least) and the addition of 200 vCPU cycles on each line of video, I decided that it was time to start looking again at some sort of Forth-like interpreted language. First off, I need to be able to simulate the vCPU behaviour - so I have started o...
by monsonite
28 Apr 2019, 16:40
Forum: Hardware and software hacking
Topic: The Gigatron Community
Replies: 0
Views: 220

The Gigatron Community

I wrote this yesterday but realised that it should have had it's own topic. Gigatron is a continually evolving platform with a vibrant community. It's barely more than 2 years since Marcel started with an empty breadboard and a bag of TTL chips. In response to today's Hackaday posting I decided to l...
by monsonite
27 Apr 2019, 13:32
Forum: Hardware and software hacking
Topic: Some ideas for an enhanced Gigatron
Replies: 5
Views: 606

Re: Some ideas for an enhanced Gigatron

Gesari, Some very interesting ideas. I have also followed your thread for an in-circuit EPROM emulator and this would be another way to make the ROM more accessible for modification. If you use fast access time RAMs (10nS) for the Romulator - then there is the option to increase the clock frequency ...
by monsonite
27 Apr 2019, 12:15
Forum: Hardware and software hacking
Topic: 10MHz, 12.5MHz and Beyond!
Replies: 24
Views: 2784

Re: 10MHz and Beyond!

Having had a time to experiment briefly with the new ROM v3y it is most noticeable the difference it makes to program execution speed - especially Tiny BASIC. Those extra 200 vCPU cycles at the end of the video line make an appreciable difference. If you take a simple program to output an incrementi...
by monsonite
27 Apr 2019, 11:28
Forum: Hardware and software hacking
Topic: 10MHz, 12.5MHz and Beyond!
Replies: 24
Views: 2784

Re: 10MHz and Beyond!

Hi Marcel, This is excellent progress, especially that you have found 12.5MHz to be stable, and then pushed on to explore 15MHz. The ROM V3y arrived in the post today - so I got a chance to try my system at 12.5MHz. I am still using a clock signal generated by an ARM microcontroller - that is not pa...
by monsonite
22 Apr 2019, 12:06
Forum: Hardware and software hacking
Topic: 10MHz, 12.5MHz and Beyond!
Replies: 24
Views: 2784

Re: 10MHz and Beyond!

Hi Marcel, This is great feedback. I appreciate the effort that you have put in over this weekend to create this proof of concept. As well as the timing gain from the 10nS RAM, I think the resistor pull-ups in the decoder section are an "easy win" to improve the low to high transition time. For my e...
by monsonite
21 Apr 2019, 15:15
Forum: Hardware and software hacking
Topic: High resolution mode?
Replies: 32
Views: 3437

Re: High resolution mode?

Marcel,

I managed to reach 10MHz with the standard 74HCT without the use of any 74F series. Hi-res mode might only involve a crystal change.