An Interview With Bil Herd - Zany Z80 Zygology

Welcome Bil Herd, designer of the Commodore C128!

• Bil grew up in Indiana saying things like "see-ment". Chris mentioned that a lot of how people say things change depending on location in the states. There was a post on /r/dataisbeautiful about this.
• He grew up grew up fixing stuff and traded for food/beer. Later he started designing synths while listening to Emerson, Lake and Palmer.
• After leaving school and wanting to fix TVs, he joined the Army nat'l guard and became a teletype repairman to get around the need for a diploma to take the TV repair class.
• Bil learned to valuable rules while doing repair:
  • Use your eyes to troubleshoot
  • "Shut up and figure it out"
• Chuck Peddle designed the 6502. He, Jeri and Bil all did a YouTube call together a few years back: https://www.youtube.com/watch?v=cns75TIrzb8
• At Bil's first design job (at the scale company), he had to make their own battery backed RAM.
• After the scale company, he was hired at Commodore (around '83, when they were working on PET/VIC). They had relocated to West Chester PA. There were 5 chip fabs on Route 30.
• Bil was told about the gig from Hedly Davis who designed the DRAM for the XBOX.
• There were early problems with the 40 column displays because of the RAS and CAS (DRAM) timing
• Commodore was in the space above the MOS fab. They were later convicted of dumping chemicals into the water table.
• A key component was the VIC (Video Interface Chip). This allowed offloading some of the video processing.
  • 6845 for CRTs
  • 6847 color (but lame)
• The VIC II integrated the concept of "sprites" (but were called a movable object block). It was "borrowed" from the TI994A.
• The TED (or TExtDisplay) chip helped for manufacturing a low cost computer (with only 121 colors) that was meant to compete with the Sinclair ZX-Spectrum.
• Bil made a video about the C116: https://www.youtube.com/watch?v=xPD5N43VIsk
• $49 16K memory based upon making their own chips (almost as much as you had to pay for just the memory by itself).
• C128 was done 5 months before CES
• When making the chips, they were 7 layers and about 150,000 transistors on a 1 uM process. The designers used Rubylith to make the lithography masks.
• There were multiple programming languages for the Commodore: C64 BASIC, C128 BASIC, CPM
• The board layout done on a VAX (C128 first board with CAD) and it was designed to work with Panasert/American Universal through hold assembly machines.
• C128 had a switching regulator which ended up benefiting some of the high draw of CPM cartridges.
• The z80 clock had to go to 4.9V in 10ns. So Bil made a workaround
• The stringent nature of FCC certifications meant that Bil couldn't add any more chips to the board...but could add transistors like above.
• There was also a need to hold reset, so he designed this circuit:
• FCC worries about the edge frequencies, because of the high harmonics of a square wave.
• There was a reflection problem that Bil fixed with a long Red/White wire. You can see it on this high res image of a C128 board.
• Bil has attended and given talks at the VCF( vintage computer forum) in the past. He also met former guest of the show Alan Wolke there.
• The Commodore 364 talked, using chips from the Magic Voice team (formerly on the Speak and Spell)
• The Zilog Z80 was added to be compatible with CPM cartridges.
• The Commodore LCD was a laptop designed and promoted, but never sold...because Marshall Smith (the CEO) was told not to by the competition.
• Instead, the Tandy Model 100 (which Dave has done videos about) went on to sell tons of units. https://www.youtube.com/watch?v=Prl6D7bqQo8
• After leaving Commodore, Bil went to work at an EMS center
• There is a movie about Amiga called "Viva Amiga" that is promised to come out soon.
• A documentary of the last day before Commodore shut down was Dave Haney's "Death Bed Vigil"
• https://www.youtube.com/watch?v=hHI7_pU0y70
• Bil believes that Commodore was doomed when Jack Tramiel left.
• The Commodore name was passed around a bunch, but Bil owns C128.com site, which has tons of great info about the era.
• He also runs a site about designing hardware and teaching people about analog/FPGAs at Herdware.com.
• These days you can see Bil making videos over on Hackaday. He was introduced to the gig v