|Older scanners often came as several possible sub-models that could connect only via a SCSI connection, OR a parallel port connection, or a USB connection. Sometimes they could connect either of two ways - e.g. USB or SCSI, or USB or parallel.|
When I searched with: Scanprisa 640P on the web, at least one "hit" said there was no parallel connected model of it,
BUT on the other hand, usually when there is a P at the end of it, as in 640P, the scanner connects via a parallel connection, NOT a SCSI connection - SCSI models often have an S at the end, e.g. 640S .
What is the full model number of the scanner ?
What is the full Product or Part number of the scanner if it also has that ?
There are several types of SCSI connector ports / matching cables. One often used for old scanners is a female 25 pin d-sub - it is identical to a standard female 25 pin parallel port connector.
If it DOES NOT have a female (pin holes) 25 pin d-sub port, if it has more contacts or pins and is a larger port, or unlikely for an old scanner, if it has a mini connector, it's definitely intended to be SCSI connected.
If it DOES have a female 25 pin d-sub port, you MUST confirm whether it's for a SCSI or a parallel connection - connecting it to the wrong type of port on the computer end will probably DAMAGE the scanner's circuits.
E.g. I have a really old HP scanner model that has a female 25 pin d-sub port that's for a SCSI connection.
Drivers for it go no higher than for Win 95 / 98 (first edition) - there are no drivers available for it for 98SE / ME or higher. I have the ISA SCSI card it came with installed on an older computer that has a mboard that has ISA slots. It works fine in Win 95 and 98.
You MAY be able to find drivers for if it can ALSO connect via USB.
You MAY be able to find drivers for it if it connects via a parallel connection.
Driver: Acer Scanprisa 640P XP
If it can only connect via a SCSI connection, older scanners often came with a ISA SCSI card, a cheaper type intended for use with only one SCSI device - XP does NOT support ANY ISA SCSI cards.
If it DID come with an ISA SCSI card, you MAY be able to get it to work with a PCI SCSI card, but buying a new one would cost you more than the scanner is worth - you MAY be able to find a used PCI SCSI card for cheap that has the right type of port.
The cable used for the female 25 pin d-sub SCSI or parallel port connection is the same for either - male 25 pin d-sub on both ends, straight through wiring.
NOTE that if it's parallel connected, the printer port mode MUST be set to EPP, ECP, or EPP / ECP, otherwise Windows cannot recognize it.
(Parallel, and probably SCSI, connected scanners and printers and all-in-ones are NOT Plug-n-Play detectable by Windows - USB connected ones ARE. You also must install drivers for the scanner when it's parallel or probably SCSI connected in order for it to be detected by Windows.)
If it's connected to the mboard's parallel port, you must make sure the printer port mode is set to one of those modes in the mboard's bios Setup - usually EPP mode works fine - ECP mode requires that the system has a dma channel available - it may not be available.
If it's connected to a PCI parallel port card, all PCI parallel port cards already support EPP or ECP mode or both.
From previous experience looking up old Acer scanners.....
Acer didn't make the scanners they sold themselves - they were re-branded models made by actual scanner manufacturers - e.g. Benq, Mirascan. The exact same scanner was often sold as the scanner manufacturer's model as well, with different labeling / branding markings. .
I found there are no crossover lists of which Acer models are identical to the scanner manufacturer's models, that I know of.
However, you MAY find "hits" on the web that say Acer Scanprisa 640P is identical to (brand) (model) .