Search found 36 matches

by monsonite
06 May 2019, 18:53
Forum: Hardware and software hacking
Topic: New form factor Gigatron.
Replies: 3
Views: 178

Re: New form factor Gigatron.

Hi All, After a few hours with EagleCAD, I have a proof of concept, reduced format pcb layout. The size is 200 x 100 mm. Power and ground planes are on the inner 2 layers, with all signals on the top or bottom layers. I have included an 8-bit output port and an 8-bit input port - as per the proposed...
by monsonite
05 May 2019, 19:14
Forum: Hardware and software hacking
Topic: Expansion bus
Replies: 48
Views: 2494

Re: Expansion bus

xopr,

I like your Tiny BASIC hack for code entry - nice.

I suppose when Tiny BASIC was written, PEEK, POKE and USR were the "tactical nukes" of the language.

I'll get a chance to try that tomorrow.

4 seconds to parse itself - is that with Mode 0 (no blank lines) video?

Ken
by monsonite
05 May 2019, 17:41
Forum: Hardware and software hacking
Topic: New form factor Gigatron.
Replies: 3
Views: 178

Re: New form factor Gigatron.

Hi All, Attached is a PDF giving an overview of the Gigatron design. I have hypothetically split the design into two roughly equal parts, loosely called "ALU" and "Memory" and then placed the sub-systems between these "camps" so as to minimise the number of signals that have to pass between them. Th...
by monsonite
04 May 2019, 20:00
Forum: Hardware and software hacking
Topic: New form factor Gigatron.
Replies: 3
Views: 178

New form factor Gigatron.

Hi All, During the life cycle of a computer, - it is not uncommon for it to undergo a series of design changes - mainly to reduce costs or to take advantage of new technology. The classic example of this metamorphosis is the PDP-8 minicomputer, which was conceived in the era of DTL (diode transistor...
by monsonite
30 Apr 2019, 18:28
Forum: Kit assembly
Topic: Assembling Gigatron the hard way
Replies: 29
Views: 492

Re: Assembling Gigatron the hard way

Well done in tracking down your instruction error to a wiring mistake. I think you deserve to win a free pcb for your perseverance and endurance ;) I think you will make much faster progress from this point onwards - and you sure have learned a lot about the machine's instruction set and architectur...
by monsonite
30 Apr 2019, 18:13
Forum: Hardware and software hacking
Topic: Expansion bus
Replies: 48
Views: 2494

Re: Expansion bus

With extra hardware comes the necessity of extra software - and with more software the requirement for more memory. Non volatile memory would be attractive - One option might be to fit a 32K x 8 ferroelectric RAM - which retains its data after power off. This could be added to the expansion board a...
by monsonite
30 Apr 2019, 17:55
Forum: Hardware and software hacking
Topic: 10MHz, 12.5MHz and Beyond!
Replies: 19
Views: 1248

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: 226

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: 226

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: 226

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...