Search found 62 matches

by monsonite
22 Apr 2019, 12:06
Forum: Hardware and software hacking
Topic: 10MHz, 12.5MHz and Beyond!
Replies: 24
Views: 2873

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: 3508

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.
by monsonite
13 Apr 2019, 10:27
Forum: Hardware and software hacking
Topic: 10MHz, 12.5MHz and Beyond!
Replies: 24
Views: 2873

Re: 10MHz and Beyond!

Hi All, Reaching 12.00MHz yesterday evening was an achievement, and so I was keen this morning to see if I can push the Gigatron even faster. Not having a 12.5MHz crystal available, nor having a 74HCT74 to act as a divide by 2 for the 25MHz crystal I do have at hand, I decided to improvise. I recent...
by monsonite
12 Apr 2019, 19:42
Forum: Hardware and software hacking
Topic: 10MHz, 12.5MHz and Beyond!
Replies: 24
Views: 2873

Re: 10MHz and Beyond!

Hi All, I can report that I now have my modified Gigatron running at 12.00MHz. Previously it would not exceed 11.0592MHz. Having replaced most of the logic with 74Fxx series, a 10nS RAM and a 45nS ROM, I found that the final push towards 12.00MHz was only achievable by reducing the value of the pull...
by monsonite
08 Apr 2019, 17:22
Forum: Hardware and software hacking
Topic: Indirect Addressing?
Replies: 8
Views: 651

Indirect Addressing?

Hi All, I'm starting to think about implementing a Tiny Forth on the Gigatron vCPU. Forth requires 2 stacks - the data stack and the return stack. If we use the usual vCPU stack with it's stack pointer at 0x1C as the data stack, is there a way of creating a second stack for the return stack with it'...
by monsonite
26 Mar 2019, 00:03
Forum: Hardware and software hacking
Topic: Late Developer
Replies: 0
Views: 253

Late Developer

A milestone passed tonight......... I downloaded CodeBlocks for Windows - so now I can use gcc and g++ to compile and run C and C++ on my laptop. I got Marcel's Gigatron Simulator gtemu.c to run on the laptop, and I am now porting gtemu across to a 400MHz STM32H743 Nucleo board - programmed with the...
by monsonite
18 Mar 2019, 18:03
Forum: Hardware and software hacking
Topic: Expansion bus
Replies: 77
Views: 7917

Re: Expansion bus

In response to mwwhited Once you have an expansion bus capable of SPI and banks of RAM, there are many ways in which this project could evolve. At the moment - the Gigatron cpu is intimately tied to the process of generating video, consuming much of the processors available clock cycles - but this n...
by monsonite
15 Mar 2019, 18:31
Forum: Hardware and software hacking
Topic: Extending WozMon
Replies: 3
Views: 427

Re: Extending WozMon

I have started to look at extending WozMon with a disassembler mode. This is mainly a learning exercise to familiarise me with vasm, but be a useful new feature in its own right. vasm is a fairly simple language to disassemble - because most of the instructions are only 2 bytes. (Compare this with Z...
by monsonite
13 Mar 2019, 21:48
Forum: Hardware and software hacking
Topic: Extending WozMon
Replies: 3
Views: 427

Extending WozMon

Last June, Marcel ported the classic 1976 Apple 1 monitor program "WozMon" to Gigatron - and with this new tool in place, Tiny BASIC followed on very shorty afterwards. Just this week, WozMon has allowed the debugging of the expansion pcb - without the need for any external resources - untethered to...
by monsonite
10 Mar 2019, 11:32
Forum: Escape Meta Alt Control Shift
Topic: Makespace Cambridge next Saturday
Replies: 4
Views: 503

Re: Makespace Cambridge next Saturday

Hi Marcel, A nostalgia trip to the birthplace of the British Computing industry? Many notable machines were developed in Cambridge - including EDSAC (6th May 1949) and of course the Acorn and Sinclair home computers (and many others). And from tiny Acorns - mighty ARMs were built. I'd like to attend...