Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!cs.utexas.edu!sun-barr!newstop!exodus!oobleck.Eng.Sun.COM!bender From: bender@oobleck.Eng.Sun.COM (I want to be eating rich soup in another town) Newsgroups: sci.electronics Subject: Re: EPROM emulator Message-ID: <11127@exodus.Eng.Sun.COM> Date: 5 Apr 91 08:47:19 GMT References: <1991Apr5.033756.276@rucs2.sunlab.cs.runet.edu> Sender: news@exodus.Eng.Sun.COM Organization: Sun Microsystems, Mt. View, Ca. Lines: 44 In article <1991Apr5.033756.276@rucs2.sunlab.cs.runet.edu> jhumphre@rucs2.sunlab.cs.runet.edu (Jeff Humphrey (Jeffus)) writes: > > The college kids' ROM emulator is here. I've been watching those > ads in Circuit Cellar for a couple of bi-months, the ones for the > 129 dollar ROM emulator. Ah, yes, the days of ROM emulators, I remember them well! In the early 80's my friend Ralph and I were in college (for EE degrees) by some magic grace, and on the side we built various devices, mostly for our electronic music hobby and for lighting control for our band and so on; stuff that was commercially available but cost $$, so we built it instead. Well, we got to the point where we were blowing EPROMS with every code change, and in the back of our minds we didn't think that EPROMS liked being programmed/erased 20 times an hour, and besides, it took a long time to blow a 2764 (we had an inexpensive EPROM programmer that didn't have any of the new intelligent programming algorithms, so the bigger the EPROM, the linearly longer the programming time). We couldn't solve the programming time problem, but we were also up against the fact that we had a finite supply of EPROMS, and eventually we got to the point where all of our EPROMS were either in the eraser (20-40 minutes) or being used in a circuit somewhere, so I built a ROM emulator. It was a small box with some 6116 SRAMS in it, a ribbon cable with a DIP plug (from Radio Schlock), a toggle switch (for write protect/program mode) and an 1/8" jack for power to keep the SRAMS powered up as we moved it from the EPROM programmer to the target system (in those days, we didn't call it a target system, we just called it the "thing" that we were working on :-). It worked pretty well, and we used it quite a bit until we could borrow 8048 and 8051 ICE's from school, which was like being in a totally new universe. I think we still used the ROM emulator for some things, but since most of our designes were single-chip 8048 and 8051 designs, we used the ICE's for most of the development. Now of course at Sun we have these ROMBOS (I kid you not on the name!) super-fancy ROM emulators with a serial port that can emulate every EPROM/ROM/PROM known to mankind, plus a few of your relatives to boot! But those days spent in the basement of our rented house until the sun came up were some of the best in my life. Have fun emulating! mike -- Won't look like rain, Won't look like snow, | DOD #000007 Won't look like fog, That's all we know! | AMA #511250 We just can't tell you anymore, We've never made oobleck before! | MSC #298726