EEVblog #1054 - How an Analog PC Joystick Works - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: January 29, 2018, 10:41:09 pm
content: How does a PC read an old school analog joystick?It might be more interesting than you think.Or how to make an ADC out of a 555 Timer...IBM PC Jr Technical Reference Manual:http://www.retroarchive.org/dos/docs/ibmpcjrtechref.pdfTandy 1000 Technical Reference Manual:https://ia801708.us.archive.org/5/items/Tandy_1000_Computer_Service_Manual_1985_Tandy/Tandy_1000_Computer_Service_Manual_1985_Tandy.pdf

author: tchicago
author_rank: Regular Contributor
timestamp: January 30, 2018, 02:00:07 am
content: You forgot to gate the WRITE signal with address decode signal when making it into a TRIG.

author: jonovid
author_rank: Super Contributor
timestamp: January 30, 2018, 04:45:51 am
content: the 555 was my 1st integrated circuit that I ever used as a kid. made many circuits with it.here is some circuits like many in electronics magazineshttp://www.talkingelectronics.com/projects/50%20-%20555%20Circuits/50%20-%20555%20Circuits.htmlhad a TRS-80 from santa, but lusted after the C64 for it's better color set. till saving up for one.static electricity was the killer of computers at the time , so I did keep out of the $$ hardware if I did not know the circuit.but software was safe to play with.BASIC language the only code I used.yes the two x & y pots was used to give the game v and h player sprite value inertia. space invaders was the game to emulate at the time.your joy v and h laser cannon sprite move horizontally back and forth . but y gave added bonus up down to your game.laser cannon sprite can be made to wraparound or pop over the screen so if your h over-shoot the end of the screenplay like space wars. trick was trying to code inertia known as inertia mechanics today. the touch screen swipe.however BASIC was slow to run the more lines you added to it. I did love the floaty FX of inertia mechanics in a games code.

author: PartialDischarge
author_rank: Super Contributor
timestamp: January 30, 2018, 07:36:17 am
content: Now, an interesting video would be to talk about the inventions of Hans Camezind,https://en.m.wikipedia.org/wiki/Hans_Camenzind

author: McBryce
author_rank: Super Contributor
timestamp: January 30, 2018, 09:04:45 am
content: The BBC Computers didn't use this method. They chose the more expensive solution and used an NEC µPD7002 12Bit A/D Converter.McBryce.

author: ggchab
author_rank: Frequent Contributor
timestamp: January 30, 2018, 11:58:43 am
content: Nice videoWhat a fantastic time when could still fully understand and control what was happening in the hardware and software of a PC. Now, anything could happen without even noticing it !Of course, we now have a lot more power and possibilities, but still ...

author: MT
author_rank: Super Contributor
timestamp: January 30, 2018, 05:01:17 pm
content: I have one of these mine are labeled Apple, it came from a computer shop closing down back in 1987, its actually a quality mechanism. Still works perfectly.

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 31, 2018, 07:27:39 am
content: Just to complicate things, at some point (mid 90s?), they added a 5V UART to the joystick port to support more channels and force feedback. I don't think there was ever a standard protocol - that was up to the driver. It did mess with some analog joysticks that connected to the pins repurposed for the UART. I presume those joysticks didn't just use RS232 because that doesn't supply enough power for force feedback.Back then, I have even seen a joystick that connected to the keyboard port with a pass through for the keyboard itself along with the joystick port. I think the intent was to allow use with games that do not natively support joysticks. No idea how well it worked in practice or how it dealt with mapping to the keyboard.

author: Kryten 2X4B
author_rank: Contributor
timestamp: February 01, 2018, 01:19:07 am
content: Dave,You said in this video that the first true micro-controller was the PIC introduced in 1993 with EEPROM on the device. Well, have a bit of a deeper look into the history before you make that kind of statement. Back in the early to mid 80's I was designing, building, and writing firmware for systems using Motorola MC68HC05 single chip micro-controllers. The MC68HC705 range had EEPROM storage with a window for UV erasure and were used mainly while you were debugging the firmware. IIRC some of the MC68HC05 parts were the same as the HC705 parts but didn't have a window for erasure so they were one time programmable (OTP) these were less expensive and used in the final product. Some people have erased the OTP parts in an X-ray machine but I don't know what the failure rate was. Intel, I think there were also similar devices available in the 8048/8051 range and possibly the 8096 range.Regards,Peter

author: McBryce
author_rank: Super Contributor
timestamp: February 01, 2018, 07:55:05 am
content: Quote from: Kryten 2X4B on February 01, 2018, 01:19:07 amActually the Motorola MC68HC805 was the first with EEPROM, the 705 had EPROM, hence the need for the window. However, the 805 (1987/88 I think) was still released about 5 years before the PIC (1993), so you are correct about the PIC not being the first.McBryce.

author: Kryten 2X4B
author_rank: Contributor
timestamp: February 02, 2018, 06:13:00 am
content: McBryce,You are correct, I meant to say EPROM. All I really wanted to say was that reprogrammable single chip micro-controllers were around well before 1993.Regards,Peter