The Amiga 4000T, also known as A4000T, was a tower version of the A4000 computer. Using the AGA chipset, it was originally released in small quantities in 1994 with a 25 MHz Motorola 68040 CPU, and re-released in greater numbers by Escom in 1995, after Commodore's demise, along with a new variant which featured a 50 MHz Motorola 68060 CPU. Despite the subsequent demise of Escom, production was continued by QuikPak in North America into at least 1997.
The A4000T was the only Amiga ever to have both SCSI and IDE interfaces built-in on the motherboard. Having driver software for both interfaces in the 512 KBROM meant that some other parts of AmigaOS had to be moved from the ROM, and thus the A4000T is the only machine to require the file "workbench.library" to be stored on disk. It was also the only Amiga to use a PC form factor for the motherboard (AT), and one of the few to use a Lithium Ion backup battery instead of a NiCd, vastly reducing the risk of an aging battery leaking corrosive fluids onto the motherboard and causing damage. Modularity was another unique aspect to the machine, with the CPU, audio, video, and input-output ports all on separate daughterboards.
The machine was targeted as a high-end video workstation with expandability in mind and an eye towards NewTek's Video Toaster. Its motherboard contains two Amiga Video Slots, five 100-pin Zorro III slots, and 4 ISA slots, and its case can accommodate up to six drives. Up to 16 MB of RAM can be installed on the motherboard, while additional RAM can be installed on some CPU boards (up to 128 MB), and yet more can be added on Zorro cards.
This was the last computer to be released by Commodore International. Only a couple hundred 4000Ts were produced before the company folded. Production of the 4000Ts was restarted after Escom bought the Amiga assets. Apart from the new option of a 68060 CPU, the Escom-manufactured 4000Ts had minor differences from the old one, including the substitution of the high density floppy drive with a double density one, and a different front bezel to the case.