News

Jul 17, 2023

Dr. Scott M. Baker Revives a Fanuc Paper

Vintage computing enthusiast and engineer Dr. Scott M. Baker has breathed new life into a faulty vintage punch-tape reader, giving his systems modern and classic a new-but-old way to load software.

Vintage computing enthusiast and engineer Dr. Scott M. Baker has breathed new life into a faulty vintage punch-tape reader, giving his systems modern and classic a new-but-old way to load software.

"In a previous video, I repaired an AKI Teletypesetter Keyboard and then modified it to allow tapes to be punched using a Raspberry Pi and, not part of the video, via serial port as well. That left me in the situation where I could write tapes, but not read them," Baker explains. "A fellow SEBHC [Society of Eight-Bit Heathkit Computerists] member, Mike, mentioned that he had recently got a deal on a Fanuc PPR [Portable Punch/Reader] on eBay, and when I saw what he had accomplished, I decided to try this myself. I found one for $200 but it was (as is usual with my luck), broken."

Punch-tapes, also known as paper tapes, were a popular alternative to the classic punch-card software storage solution throughout the early days of computing. Based on technology originally developed for weaving looms and later repurposed to drive player pianos, the rolls of tape had one major advantage over cards: if you dropped one, you didn't have to spend the next few hours laboriously putting individual cards back in the right order.

Released in the early 1980s, the Fanuc PPR combines printer, punch, and reader in a single unit. Data is literally "punched" onto a paper tape, creating holes which can later be read optically or via mechanical means. "When I received my PPR from the eBay seller, it didn’t work," Baker writes. "That's alright, it was listed as 'parts/repair.' The symptom was that when powered on, all LEDs would stay lit and the keypad was non-responsive. The manual troubleshoots this as 'logic board failure' and says to replace the logic board."

With spares not exactly readily available, though, Baker opted instead to diagnose the issue and fix the existing logic board. Finding fault in two custom chips for which replacements were in short supply, Baker was able to ascertain their purpose as a crystal oscillator — easily replaced with an off-the-shelf equivalent and a bit of bodge wiring. "That was enough to get it clocking and to get it fetching," Baker says, "but I still had stuck LEDs on the logic board and the buttons were as responsive as an inert lump of coal."

That turned out to be an issue with a serial driver chip, likely toasted when the machine was incorrectly wired to a non-compatible or otherwise faulty device. Replacing that kicked the machine into life, followed by a minor fix for a jumpy auto-reset circuit.

Finally, Baker wired the reader up to two machines: a modern RC2014, a modular Zilog Z80-based microcomputer, via a custom two-port serial board; and a Heathkit H8 kit computer, which has received a widerange of impressiveupgrades prior to the addition of the Fanuc PPR.

Baker's full write-up is available on his website, with additional information in the above video.