But how do you program a chip in circuit rather than on the development board? On 14 February 2014 21:00, David wrote: > On 14/02/2014 20:41, David C Brown wrote: > > I have just built a small circuit using seven 74F TTL chips which works > > fairly well at 50MHz. I would now like to cram it into a single chi an= d > > speed it up a tad. . Casting my mind back many years when I was workin= g > we > > used devices called GALs from Lattice and I suspect that SPLDs are the > > modern equivalent. > > > > Questions. Would these devices work at 80MHz? Who is the favourite > > manufacturer? How do you program them? > > I can only answer your question as a hobbyist, but I have successfully > used a Lattice CPLD[1] for exactly this. I followed a 74xx circuit > online and implemented it using a mixture of schematics and VHDL inside > an ispMACH 4000. The development board[2] I used was under <=A320. > > Programming is very easy - they supply a USB cable and the ispLEVER > software is available from the website. You can draw a schematic with > components that mostly match 74xx equivalents, map input & output pins > to real pins and then synthesise the whole design. The resulting file > is downloaded to the board using ispVM. > > All the software is free but requires licensing, very common for > CPLD/FPGA development environments. I found that a bit of a pain, but > you only have to do it once. > > There are some LEDs on the board which can be used for status output but > apart from that the board is very bare, which suited me fine. > > David > > 1 - http://www.latticesemi.com/Products/FPGAandCPLD.aspx > > 2 - > > http://uk.farnell.com/lattice-semiconductor/lc4256ze-b-evn/board-breakout= -ispmach-4256ze/dp/2253064 > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 __________________________________________ David C Brown 43 Bings Road Whaley Bridge High Peak Phone: 01663 733236 Derbyshire eMail: dcb.home@gmail.com SK23 7ND web: www.bings-knowle.co.uk/dcb --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .