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.
Search found 101 matches
- 21 Apr 2019, 15:15
- Forum: Hardware and software hacking
- Topic: High resolution mode?
- Replies: 38
- Views: 39245
- 13 Apr 2019, 10:27
- Forum: Hardware and software hacking
- Topic: 10MHz, 12.5MHz and Beyond!
- Replies: 45
- Views: 56728
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...
- 12 Apr 2019, 19:42
- Forum: Hardware and software hacking
- Topic: 10MHz, 12.5MHz and Beyond!
- Replies: 45
- Views: 56728
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...
- 08 Apr 2019, 17:22
- Forum: Hardware and software hacking
- Topic: Indirect Addressing?
- Replies: 8
- Views: 6112
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'...
- 26 Mar 2019, 00:03
- Forum: Hardware and software hacking
- Topic: Late Developer
- Replies: 0
- Views: 9853
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...
- 18 Mar 2019, 18:03
- Forum: Hardware and software hacking
- Topic: Expansion bus
- Replies: 98
- Views: 94966
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...
- 15 Mar 2019, 18:31
- Forum: Hardware and software hacking
- Topic: Extending WozMon
- Replies: 3
- Views: 3213
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...
- 13 Mar 2019, 21:48
- Forum: Hardware and software hacking
- Topic: Extending WozMon
- Replies: 3
- Views: 3213
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 - unt...
- 10 Mar 2019, 11:32
- Forum: Escape Meta Alt Control Shift
- Topic: Makespace Cambridge next Saturday
- Replies: 4
- Views: 4581
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...
- 08 Mar 2019, 20:30
- Forum: Hardware and software hacking
- Topic: 10MHz, 12.5MHz and Beyond!
- Replies: 45
- Views: 56728
Re: 10MHz and Beyond!
Hi All, After a year of inactivity - I have caught the Gigatron bug again. In May 2018 I was able to tweak the clock frequency up to 10.00MHz and still have the Blinkenlights run - just 160% of their normal speed. Tonight, I have reduced the value of C1 and C2 in the crystal oscillator circuit from ...