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An 8 bit TTL CPU in 16 chips: CSCvon8 http://anycpu.org/forum/viewtopic.php?f=3&t=588 |
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Author: | BigEd [ Fri Apr 05, 2019 4:58 pm ] |
Post subject: | An 8 bit TTL CPU in 16 chips: CSCvon8 |
. This very small CPU design implemented in TTL might be of interest, 8 bits and only 16 chips: See also Warren's previous tiny machine: Warren’s Crazy Small CPU (4 bit machine, 11 chips) See also previously |
Author: | monsonite [ Sat Apr 06, 2019 9:20 am ] |
Post subject: | Re: An 8 bit TTL CPU in 16 chips: CSCvon8 |
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/elec ... 27C322.pdf This is in a 42 pin DIP and will require a special eprom programmer and adaptor socket to program - which may be a limiting factor to some home constructors. The access time of the large ROM used in the ALU is 80nS which will be a limiting factor to the clock frequency. Similarly the decode logic ROM has at best a 45nS access time. Nevertheless, the design shows how an 8 bit Von Neumann architecture can be implemented in a handful of TTL devices and four large memory chips. The project detail, including devices used, instruction set etc can be found from this link: https://github.com/DoctorWkt/CSCvon8/bl ... _design.md |
Author: | BigEd [ Sat Apr 06, 2019 6:50 pm ] |
Post subject: | Re: An 8 bit TTL CPU in 16 chips: CSCvon8 |
An interesting observation: not so many chips, but a great many transistors! Those are big EPROMs in impressively big packages. Still, the principle of making moderately simple hardware and then putting the detail into a lookup table or in microcode is a good one, when those things are cheap. |
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