which EPROM eraser and programmer? - Page 1
Forum section: electronics / beginners

author: drakke
author_rank: Regular Contributor
timestamp: April 21, 2015, 05:33:17 pm
content: I am building a 8088 single board computer (using the Walter Fuller book) that uses 27C256-20 32Kx8 EPROM chips that I need to program.http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?search_type=jamecoall&catalogId=10001&freeText=27C256-20&langId=-1&productId=39722&storeId=10001&ddkey=http:StoreCatalogDrillDownViewWhat EPROM eraser and programmer will I need?If these can be used in other projects I would like to get one with reasonable quality but if they are not particularly useful (this is a pretty old design) then I would like to get something cheap.Thanks.

author: rsjsouza
author_rank: Super Contributor
timestamp: April 21, 2015, 05:58:13 pm
content: A programmer is the popular TL866, evenreviewed by Dave.EPROM erasers can be anything, even the sunlight. For a good selection, there is a lot of dirt cheap ones on eBay but I can't attest for their quality (although I am unsure if you can go really wrong with a timer and the correct UV wavelength light bulb).

author: Mechanical Menace
author_rank: Super Contributor
timestamp: April 21, 2015, 06:02:30 pm
content: Personally I'd spend that little more on EEPROMs instead of EPROMs. Less hassle tbh. Plus it may actually be cheaper getting higher capacity EEPROMs and just not using the extra address and/or data lines.As for programming do you not have anything about you could repurpose for the job? Say an Arduino? Or if you have a PC with a parallel port you could check out somethinglike thisEDIT: The Hackaday article links go nowhere, but some time spent on Google should find you something.

author: smjcuk
author_rank: Frequent Contributor
timestamp: April 21, 2015, 06:10:32 pm
content: +1 for EEPROMs. I spent two years of my youth trying to build a Z80 SBC and most of that was erasing EPROMs after stupid mistakes. Never ever again.

author: drakke
author_rank: Regular Contributor
timestamp: April 21, 2015, 06:52:09 pm
content: Quote from: smjcuk on April 21, 2015, 06:10:32 pmI'm sold. Can I replace the 27C256-20 with a 28C256?http://www.futurlec.com/Memory/28C256.shtml27C256-20200ns access time20 mA Active current100 uA Standby current28-pin Dual-in-line package28C256150 ns access time50 mA Active Current200 uA CMOS Standby Current28-lead PDIPI also saw this which seems to indicate they are compatible:http://electronics.stackexchange.com/questions/57857/replacing-27c256-with-28c256-how-to-wire-weI am a beginner, so anything I missed?Thanks.

author: smjcuk
author_rank: Frequent Contributor
timestamp: April 21, 2015, 07:42:10 pm
content: Occasionally there is wait state logic for memory access if the CPU is faster than the memory device so you'll need to check timings etc on both the CPU and the EEPROM datasheet. I'm rusty as hell on that so I'd wait for further advice. However its faster than the 27C256 so I doubt there will be problems if it's a proven design.Also check the programming voltages for the EEPROM as some devices have different voltages for writes/erases.

author: Mechanical Menace
author_rank: Super Contributor
timestamp: April 22, 2015, 10:45:48 am
content: Quote from: smjcuk on April 21, 2015, 07:42:10 pmGiven the vintage I'd be surprised if even slow ROMs aren't faster than the 8088.QuoteApart from the waiting for further advice +1. If it doesn't work you have something to fix which is a learning exercise in itself.QuoteWhich would only really be a problem with a DIY programmer...