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Message |
Forum: Hardware in general Topic: The LD12 - a TTL PDP-8 kit from 1974 |
| monsonite |
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Posted: Wed May 29, 2019 3:57 pm
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Replies: 7
Views: 18072
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| Hi Ed, I hope this fills the big gap in the details of the real hardware that was used to support the Prosser and Winkel textbook http://anycpu.org/forum/viewtopic.php?f=3&t=608 I think that the main logic board was intended to support a variety of minicomputer designs, the PDP-8 being just the ... |
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Forum: General Discussions Topic: The Art of Digital Design - useful book resource |
| monsonite |
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Posted: Wed May 29, 2019 1:37 pm
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Replies: 6
Views: 5005
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| Thanks Ed, I have already fallen down a digital "rabbit hole" - and found the complete design documentation to the LD20's predecessor - the LD12 - a complete kit to build a PDP-8 functional clone in TTL, from 1974. I've posted links to this resource under a new topic in the Hardware sectio... |
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Forum: Hardware in general Topic: The LD12 - a TTL PDP-8 kit from 1974 |
| monsonite |
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Posted: Wed May 29, 2019 1:32 pm
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Replies: 7
Views: 18072
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| Following my interest in the LD20 - mentioned in "The Art of Digital Design" http://anycpu.org/forum/viewtopic.php?f=3&t=608 After a lot of Googling, I discovered that it had a predecessor known as the LD12. This was essentially a DIY kit for a functionally equivalent clone of the PDP-... |
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Forum: General Discussions Topic: The Art of Digital Design - useful book resource |
| monsonite |
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Posted: Wed May 29, 2019 11:42 am
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Replies: 6
Views: 5005
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| People have used that book to build an actual PDP-8. The book focuses on Top Down Design - and makes use of Algorithmic State Machines. The architecture and logic design of the PDP-8 is covered in sufficient detail in Chapter 7 - and proceeds to present the design of a machine they called the LD-20... |
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Forum: General Discussions Topic: The Art of Digital Design - useful book resource |
| monsonite |
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Posted: Sun May 26, 2019 10:44 am
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Replies: 6
Views: 5005
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| This book by Winkel and Prosser is one of the classic computer engineering textbooks of the 1980s. The first edition (1980) was written at a time when microcomputers were still rare - and the university lab was more likely to have a PDP-8/E minicomputer running experimental equipment, rather than an... |
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Forum: Hardware in general Topic: Gigatron - A TTL machine with integrated VGA |
| monsonite |
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Posted: Mon Apr 29, 2019 5:34 pm
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Replies: 25
Views: 21075
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| Hi All, This weekend we got two Gigatron machines running at 12.5MHz or better. I managed a rather jittery 12.5MHz whilst Marcel's machine built on a 4 layer board managed 15MHz. The increase in clock frequency means that the video display only takes half of the CPU time, leaving 200 cycles at the e... |
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Forum: General Discussions Topic: Sweet 16 - because everybody loves registers |
| monsonite |
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Posted: Sat Apr 13, 2019 6:26 pm
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Replies: 3
Views: 4720
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| There has been a fair bit written about Sweet 16 - a 16-bit virtual processor devised by Steve Wozniak in 1976/77 in order to simplify the handling of 16-bit instructions on the Apple 1 - which was an 8-bit 6502 and was somewhat short of registers. Woz devised a virtual 16 bit machine with a bank of... |
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Forum: Hardware in general Topic: Gigatron - A TTL machine with integrated VGA |
| monsonite |
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Posted: Sat Apr 13, 2019 11:22 am
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Replies: 25
Views: 21075
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| Hi All, I've had my Gigatron for about a year, bought initially to jumpstart my learning about TTL computers. In just 34 basic TTL chips - here was a machine that could compete with commercial machines based on microprocesors, such as the 6502 or Z80, yet had a much simpler and more easily understoo... |
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Forum: General Discussions Topic: An 8 bit TTL CPU in 16 chips: CSCvon8 |
| monsonite |
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Posted: Sat Apr 06, 2019 9:20 am
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Replies: 2
Views: 4141
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| An interesting design - utilising heavily upon the availability of large ROMS The ALU is implemented using a M27C322 2Mx16 bit EPROM and the decode logic is performed using a M27C1024 64K x 16 EEPROM. https://processmodeling.org/theory/electronics/ref/micro/eprom/27C322.pdf This is in a 42 pin DIP a... |
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Forum: Hardware in general Topic: From Nand to Tetris - the Elements of Computing Systems |
| monsonite |
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Posted: Thu Mar 28, 2019 8:31 am
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Replies: 7
Views: 6046
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| Hi Arne, I agree, the PDP-8 schematics are quite difficult to interpret. You can pick out the basic flip-flops, but it's the vast amounts of surrounding diode steering logic which really confuses the newcomer. It doesn't help that it it is all based on PNP devices with negative supply rails to furth... |
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Forum: Hardware in general Topic: From Nand to Tetris - the Elements of Computing Systems |
| monsonite |
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Posted: Wed Mar 27, 2019 8:20 pm
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Replies: 7
Views: 6046
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| Now I can understand much better how the Apollo navigation guidance computer might be realized - all 3 input NORs IIRC. Hi Arne - it was the Apollo Guidance computer that first set me off on this journey. I was intrigued how a complex machine could just be made from simple logic - provided that you... |
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Forum: Hardware in general Topic: From Nand to Tetris - the Elements of Computing Systems |
| monsonite |
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Posted: Wed Mar 27, 2019 5:42 pm
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Replies: 7
Views: 6046
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| I have replaced the low resolution screen-shot of the Hack Bitslice with the following PDF: HACK_bitslice_regs_13.pdf ALU The ALU has two inputs which can be set to zero with control signals ZX and ZY (IC5, IC6) and also inverted/negated with NX and NY (IC3, IC4) After zero and negation, the inputs ... |
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Forum: Hardware in general Topic: From Nand to Tetris - the Elements of Computing Systems |
| monsonite |
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Posted: Tue Mar 26, 2019 11:26 pm
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Replies: 7
Views: 6046
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| N2T has been mentioned several times on this forum, but it is certainly relevant with the recent interest in TTL computers. https://www.nand2tetris.org/ In 2013, I came across the N2T course and bought the book "The Elements of Computer Systems" and embarked on studying the simple 16-bit &... |
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Forum: General Discussions Topic: Late Developer |
| monsonite |
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Posted: Tue Mar 26, 2019 2:26 pm
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Replies: 3
Views: 4286
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| And whatever you are doing with your STM32H473 - even a dumb parallel output requires its clock (!) to be enabled first. I have a hardware background - mostly pcb design with ARM devices for about the last 5 years. I can write enough C code to set up an STM32 and get it running - but mostly, these ... |
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Forum: General Discussions Topic: Late Developer |
| monsonite |
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Posted: Tue Mar 26, 2019 12:08 am
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Replies: 3
Views: 4286
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| A major milestone passed tonight......... (only took 35 years) 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 van Kervinck's Gigatron Simulator gtemu.c to run on the laptop, and I am now porting gtemu across to a 400MHz ST... |
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