From the look of the arm, it's an early version of the DW728. In about 1990 it was called the 1600S 1 or 3* according to the supply. This
could be younger as it has the emergncy stop button on top. It should be able to crosscut somewhat more than 600mm x 25mm. The guard accepts blades up to 350mm, but for precision work the 1970 catalogue reccomends 11" /280mm. Later, the blade size was upped by the marketing department... at least we did not get the "developed HP" swindle in the UK! Yours should have an 8 bearing roller head. The long arm version (almost 1M) only had a 4 bearing head. On 2nd hand models, bits of the guards are often missing... Yours may still have some anti kick back fingers and a riving knife you can lower for rip cuts - now not considered safe. I must admit using mine to rip, but it has a custom built 2M table and roller outfeed, so I can size sheet goods on my own. Treewood ripping is by bandsaw.
The set up is convered in the 728 manual downloadable from the DW site, or much better, have a look at mrsawdust.com. Wally Kunkel was long involved with DeWalt since before the purchase by B&D. Now deceased, his family run an interior finishing service for banks, boardrooms, grand house libraries etc, and still rely on the RAS. Wally was involved in both sales, demos and training courses and his book is worth getting via the website. The intro also includes a fascinating history of the RAS. As Americans, of course they love to use the RAS with a dado head and often use it for jobs better done by spindle or router - but interesting just the same. However, the set up chapters would help someone new to the RAS. There's also another useful book you might find second hand - Fine Tuning Your Radial Arm Saw by Jon Eakes - Amazon has copies at a ludicrous price or a .pdf at
https://www.google.com/search?client=fi ... radial+arm
for free. This deals with DIY models, but the principles apply to any RAS.
* 1phase 2.5HP, 3phase 4HP (I think)