Re: so far off topic - capatob - saratov2 computer Russsian pdp8?
On 01/07/2019 07:51 PM, allison via cctalk wrote: I still want to make a stretched 8, PDP8 ISA with 16 bits and faster. No good reason save for it wold be fun. Umm, I think that is called a Data General Nova! Jon
Re: so far off topic - capatob - saratov2 computer Russsian pdp8?
On 01/07/2019 07:25 PM, ben via cctalk wrote: > On 1/7/2019 8:20 AM, allison via cctalk wrote: > snip... >> made though more likely 74F, AS, or LS variant and of course CMOS 74ACT >> (and cmos friends) as I just bought a bunch. Dip is getting harder to >> get but >> the various SMT packages are easy. Prices for 10 or more of a part are >> cheap to cheaper from primary suppliers. The second tier suppliers are >> often several times that. > > I got ebay... The bottom of the heap. > >> I figure most of what I did back then is years before many here were >> born. >> >> However I have enough NOS TTL 74LS, 74AS, 74F series to build several >> machines. > > I have been playing around with a early 70's TTL computer design > and 74LS181's are too slow by 30 ns. Using a BLACK BOX model for core > memory, I can get a 1.2us memory cycle using a 4.912 MHz raw clock > but I need a few 74Hxx's in there. Proms are 256x4 60 ns and 32x8 50 ns. > > Do you have your 74Hxx spares? Eastern Europe still has a few on ebay > with reasonable shipping for 100% American Russian parts. > No use for 74H parts though I have a bunch. the 74LS are slow you are paying for lower power with speed. tHe 74181 and 74S181 were far faster. Proms are small and slow, last time I used them was for the address decode used on the Northstar* MDS-A controller. I built the last big machine with ram back 1980 and was in the 1us instruction cycle time for single cycle instructions without pipelines. Core was never considered. Trick is throw hardware at it. Adding adders to the address calculation rather than reuse the ALU saves a lot of time and wires. Not like it was for manufacture or anything like that. More of an exercise. I still want to make a stretched 8, PDP8 ISA with 16 bits and faster. No good reason save for it wold be fun. >> I'm still building, current project is a very compact Z80 CP/M system >> using CF >> for disk. Mine uses all Zilog CMOS for very low power. Its a variant of >> the >> Grant Searle Z80 with memory management added to utilize all of the >> 124k ram and eeprom. If you want go look there. > > What do you use all that memory for? > CP/M the allocation block store for each drive and deblocking buffers for performance can be large plus its easy to hide part of the Bios in banked ram. Background processes are easier when you have lots of ram for that. Most of the larger aps like C compilers and such run better with more than 48K, 56k is easy, and 60k is doable with the right memory map. For EEprom its more than boot, the system is in EEprom (about 8K) and with 32K or more things like romdisks and utilities are easily parked there. I've been building nonstandard CP/M systems since 79. In all cases he aps think it is standard CP/M but the bios and such have been tuned even CP/M Bdos it self. Though I often use ZRdos or ZSdos as they are very good. Not much you cant do to it. Allison >> > > The Chinese elves have been busy, My 5V 15 amp $20 power supply arrived > in the mail today. I have power to spare for my BUS and blinking lights. > So long as you load it at least 10% it will be good. > Ben. > >
Re: so far off topic - capatob - saratov2 computer Russsian pdp8?
On 1/7/2019 8:20 AM, allison via cctalk wrote: snip... made though more likely 74F, AS, or LS variant and of course CMOS 74ACT (and cmos friends) as I just bought a bunch. Dip is getting harder to get but the various SMT packages are easy. Prices for 10 or more of a part are cheap to cheaper from primary suppliers. The second tier suppliers are often several times that. I got ebay... The bottom of the heap. I figure most of what I did back then is years before many here were born. However I have enough NOS TTL 74LS, 74AS, 74F series to build several machines. I have been playing around with a early 70's TTL computer design and 74LS181's are too slow by 30 ns. Using a BLACK BOX model for core memory, I can get a 1.2us memory cycle using a 4.912 MHz raw clock but I need a few 74Hxx's in there. Proms are 256x4 60 ns and 32x8 50 ns. Do you have your 74Hxx spares? Eastern Europe still has a few on ebay with reasonable shipping for 100% American Russian parts. I'm still building, current project is a very compact Z80 CP/M system using CF for disk. Mine uses all Zilog CMOS for very low power. Its a variant of the Grant Searle Z80 with memory management added to utilize all of the 124k ram and eeprom. If you want go look there. What do you use all that memory for? Allison The Chinese elves have been busy, My 5V 15 amp $20 power supply arrived in the mail today. I have power to spare for my BUS and blinking lights. Ben.
Re: so far off topic - capatob - saratov2 computer Russsian pdp8?
On 01/07/2019 09:51 AM, Peter Corlett via cctalk wrote: > On Sun, Jan 06, 2019 at 02:54:08PM -0700, ben via cctalk wrote: >> On 1/6/2019 12:24 PM, allison via cctalk wrote: >>> The small beauty of being there... FYI back then (1972) a 7400 was about >>> 25 cents and 7483 adder was maybe $1.25. Least that's what I paid. >> Checks my favorite supplier. >> $1.25 for 7400 and $4.00 for a 7483. >> It has gone up in price. > Thanks to inflation, $0.25 in 1972 is worth $1.51 now. Likewise, $1.25 has > inflated to $7.54. So they're cheaper in real terms than they used to be. > > However, it's still not entirely comparable, as I suspect nobody's making > 74-series chips any more so you're buying NOS. A modern equivalent would be a > microcontroller, which start at well under a dollar. > First I wasn't guessing back. I was building and buying back then. So that was what I actually paid in 1972, I've been at it since RTL hit the streets. The 74 series still made though more likely 74F, AS, or LS variant and of course CMOS 74ACT (and cmos friends) as I just bought a bunch. Dip is getting harder to get but the various SMT packages are easy. Prices for 10 or more of a part are cheap to cheaper from primary suppliers. The second tier suppliers are often several times that. I figure most of what I did back then is years before many here were born. However I have enough NOS TTL 74LS, 74AS, 74F series to build several machines. I'm still building, current project is a very compact Z80 CP/M system using CF for disk. Mine uses all Zilog CMOS for very low power. Its a variant of the Grant Searle Z80 with memory management added to utilize all of the 124k ram and eeprom. If you want go look there. Allison
